The cost-effectiveness of herpes simplex virus-2 suppressive therapy with daily aciclovir for delaying HIV disease progression among HIV-1-infected women in South Africa

20 years of herpes simplex virus type 2 (HSV-2) research in low-income and middle-income countries: systematic evaluation of progress made in addressing WHO priorities for research in HSV-2/HIV interactions, HSV-2 control and mathematical modelling

INTRODUCTION

Reviewing and updating research priorities is essential to assess progress and to ensure optimal allocation of financial and human resources in research. In 2001, WHO held a research priority setting workshop for herpes simplex virus type 2 (HSV-2) research in low-income and middle-income countries (LMICs). This study aimed to describe progress between 2000 and 2020 in three of the five key research priority areas outlined in the workshop: HSV-2/HIV interactions, HSV-2 control measures and HSV-2 mathematical modelling. The remaining priorities are addressed in a companion paper.

METHOD

A systematic literature search of MEDLINE, CINAHL, Global Health and Cochrane databases was carried out. Relevant primary research studies based in LMICs, written in English and published on 2000-2020 were included. Papers were screened by two independent reviewers, and suitable variables were selected for manual extraction from study texts. Data were organised into an Excel spreadsheet and analysed using IBM SPSS.

RESULTS

In total, 3214 discrete papers were identified, of which 180 were eligible for inclusion (HSV-2/HIV interactions, 98; control measures, 58; mathematical modelling, 24). Most studies were conducted in East Africa. The majority of the 2001 WHO HSV-2 research priorities were addressed at least in part. Overall, despite several studies describing a strong relationship between HSV-2 and the acquisition and transmission of HIV, HSV-2 control repeatedly demonstrated little effect on HIV shedding or transmission. Further, although mathematical modelling predicted that vaccines could significantly impact HSV-2 indicators, HSV-2 vaccine studies were few. Studies of antiviral resistance were also few.

CONCLUSION

Since 2000, LMIC HSV-2 research addressing its control, HIV interactions and mathematical modelling has largely addressed the priorities set in the 2001 WHO HSV-2 workshop. However, key knowledge gaps remain in vaccine research, antiviral cost-effectiveness, antiviral resistance and specific geographical areas.

Estimated economic burden of genital herpes and HIV attributable to herpes simplex virus type 2 infections in 90 low- and middle-income countries: A modeling study

BACKGROUND

Economic losses due to herpes simplex infections in low- and middle-income countries (LMICs) are unknown. We estimated economic and quality-of-life losses due to genital herpes in 2019, in 90 LMICs, and from 2020 to 2030 in 45 countries in the World Health Organization (WHO) Africa. We additionally estimated economic losses due to human immunodeficiency virus (HIV) attributable to herpes simplex virus type 2 (HSV-2) infections.

METHODS AND FINDINGS

We estimated genital herpes-related spending on treatment, wage losses due to absenteeism, and reductions in quality of life, for individuals aged 15 to 49 years, living with genital herpes. Had HSV-2 had contributed to the transmission of HIV, we estimated the share of antiretroviral treatment costs and HIV-related wage losses in 2019 that can be attributed to incident and prevalent HSV-2 infections in 2018. For the former, we used estimates of HSV-2 incidence and prevalence from the global burden of disease (GBD) study. For the latter, we calculated population attributable fractions (PAFs), using the classic (Levin's) epidemiological formula for polytomous exposures, with relative risks (RRs) reported in literature. To extend estimates from 2020 to 2030, we modeled the transmission of HSV-2 in 45 African countries using a deterministic compartmental mathematical model, structured by age, sex, and sexual activity, which was fitted to seroprevalence gathered from a systematic review and meta-regression analysis. In the 90 LMICs, genital herpes contributed to US$813.5 million in treatment and productivity losses in 2019 (range: US$674.4 to US$952.2 million). Given observed care-seeking and absenteeism, losses are in the range of US$29.0 billion (US$25.6 billion to US$34.5 billion). Quality-of-life losses in the amount of 61.7 million quality-adjusted life years (QALYs) are also possible (50.4 million to 74.2 million). The mean annual cost of treatment and wage losses per infection is US$183.00 (95% CI: US$153.60 to US$212.55); the mean annual cost of quality-of-life losses is US$343.27 (95% CI: 272.41 to 414.14). If HSV-2 has fueled the transmission of HIV, then seroprevalent HSV-2 cases in 2018 can account for 33.2% of the incident HIV infections in 2019, with an associated antiretroviral therapy (ART) cost of US$186.3 million (range: US$163.6 to US$209.5 million) and 28.6% of HIV-related wage losses (US$21.9 million; range: US$19.2 to US$27.4 million). In the WHO Africa region, the 3.9 million seroprevalent genital herpes cases from 2020 to 2030 contributed to US$700.2 million in treatment and productivity losses. Additionally, quality-of-life losses in the range of 88 million to 871 million QALYs are also possible. If HSV-2 has contributed to the transmission of HIV, then in 2020, the PAF of HIV due to prevalent HSV-2 will be 32.8% (95% CI: 26.7% to 29.9%) and due to incident infections will be 4.2% (95% CI: 2.6% to 3.4%). The PAF due to prevalent infections will decline to 31.0% by 2030 and incident infections to 3.6%. Though we have accounted for the uncertainty in the epidemiological and economic parameter values via the sensitivity analysis, our estimates still undervalue losses due to limiting to the 15- to 49-year-old population.

CONCLUSIONS

Economic losses due to genital herpes in LMICs can be large, especially when considering the lifelong nature of the disease. Quality-of-life losses outweigh spending on treatment and reductions in productivity. If HSV-2 has contributed to the spread of HIV in LMICs, then nearly one third of antiretroviral costs and HIV-related wage losses can be attributed to HSV-2. Given the magnitude of the combined losses, a vaccine against HSV-2 must be a global priority.

Healthcare resource utilisation pattern and costs associated with herpes simplex virus diagnosis and management: a systematic review

OBJECTIVES

Little is known about the economic burden of herpes simplex virus (HSV) across countries. This article aims to summarise existing evidence on estimates of costs and healthcare resource utilisation associated with genital and neonatal HSV infection.

DESIGN

Systematic literature review.

DATA SOURCES

Seven databases were searched from inception to 31 August 2020. A focused search was performed to supplement the results.

ELIGIBILITY CRITERIA

Studies which reported either healthcare resource utilisation or costs associated with HSV-related healthcare, including screening, diagnosis and treatment of genital HSV infection and neonatal herpes prevention and treatment.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted data and assessed the risk of bias using the Larg and Moss's checklist. All data were summarised narratively.

RESULTS

Out of 11 443 articles, 38 were included. Most studies (35/38, 94.6%) were conducted in high-income countries, primarily the United States, and were more often related to the prevention or management of neonatal herpes (n=21) than HSV genital ulcer disease (n=17). Most analyses were conducted before 2010. There was substantial heterogeneity in the reporting of HSV-related healthcare resource utilisation, with 74%-93% individuals who sought care for HSV, 11.6%-68.4% individuals who received care, while neonates with herpes required a median of 6-34 hospitalisation days. The costs reported were similarly heterogeneous, with wide variation in methodology, assumptions and outcome measures between studies. Cost for screening ranged from US$7-100, treatment ranged from US$0.53-35 for an episodic therapy, US$240-2580 yearly for suppressive therapy, while hospitalisation for neonatal care ranged from US$5321-32 683.

CONCLUSIONS

A paucity of evidence exists on healthcare resource utilisation and costs associated with HSV infection, especially among low-income and middle-income countries. Future research is needed on costs and healthcare utilisation patterns to improve overall understanding of the global economic burden of HSV.

Integrating HIV services and other health services: A systematic review and meta-analysis

BACKGROUND

Integration of HIV services with other health services has been proposed as an important strategy to boost the sustainability of the global HIV response. We conducted a systematic and comprehensive synthesis of the existing scientific evidence on the impact of service integration on the HIV care cascade, health outcomes, and cost-effectiveness.

METHODS AND FINDINGS

We reviewed the global quantitative empirical evidence on integration published between 1 January 2010 and 10 September 2021. We included experimental and observational studies that featured both an integration intervention and a comparator in our review. Of the 7,118 unique peer-reviewed English-language studies that our search algorithm identified, 114 met all of our selection criteria for data extraction. Most of the studies (90) were conducted in sub-Saharan Africa, primarily in East Africa (55) and Southern Africa (24). The most common forms of integration were (i) HIV testing and counselling added to non-HIV services and (ii) non-HIV services added to antiretroviral therapy (ART). The most commonly integrated non-HIV services were maternal and child healthcare, tuberculosis testing and treatment, primary healthcare, family planning, and sexual and reproductive health services. Values for HIV care cascade outcomes tended to be better in integrated services: uptake of HIV testing and counselling (pooled risk ratio [RR] across 37 studies: 1.67 [95% CI 1.41-1.99], p < 0.001), ART initiation coverage (pooled RR across 19 studies: 1.42 [95% CI 1.16-1.75], p = 0.002), time until ART initiation (pooled RR across 5 studies: 0.45 [95% CI 0.20-1.00], p = 0.050), retention in HIV care (pooled RR across 19 studies: 1.68 [95% CI 1.05-2.69], p = 0.031), and viral suppression (pooled RR across 9 studies: 1.19 [95% CI 1.03-1.37], p = 0.025). Also, treatment success for non-HIV-related diseases and conditions and the uptake of non-HIV services were commonly higher in integrated services. We did not find any significant differences for the following outcomes in our meta-analyses: HIV testing yield, ART adherence, HIV-free survival among infants, and HIV and non-HIV mortality. We could not conduct meta-analyses for several outcomes (HIV infections averted, costs, and cost-effectiveness), because our systematic review did not identify sufficient poolable studies. Study limitations included possible publication bias of studies with significant or favourable findings and comparatively weak evidence from some world regions and on integration of services for key populations in the HIV response.

CONCLUSIONS

Integration of HIV services and other health services tends to improve health and health systems outcomes. Despite some scientific limitations, the global evidence shows that service integration can be a valuable strategy to boost the sustainability of the HIV response and contribute to the goal of 'ending AIDS by 2030', while simultaneously supporting progress towards universal health coverage.

Modeling HIV disease progression and transmission at population-level: The potential impact of modifying disease progression in HIV treatment programs

INTRODUCTION

Mathematical models that incorporate HIV disease progression dynamics can estimate the potential impact of strategies that delay HIV disease progression and reduce infectiousness for persons not on antiretroviral therapy (ART). Suppressive treatment of HIV-positive persons co-infected with herpes simplex virus-2 (HSV-2) with valacyclovir, an HSV-2 antiviral, can lower HIV viral load, but the impact of partially-suppressive valacyclovir relative to fully-suppressive ART on population HIV transmission has not been estimated.

METHODS

We modeled HIV disease progression as a function of changes in viral load and CD4 count over time among ART naïve persons. The disease progression Markov model was nested within a dynamic model of HIV transmission at population level. We assumed that valacyclovir reduced HIV viral load by 1.23 log copies/μL, and that persons treated with valacyclovir initiated ART more rapidly when their CD4 fell below 500 due to retention in HIV care. We estimated the potential impact of valacyclovir on onward transmission of HIV in three scenarios of different ART and valacyclovir population coverage.

RESULTS

The average duration of HIV infection was 9.5 years. The duration of disease before reaching CD4 200cells/μL was 2.53 years longer for females than males. Relative to a baseline of ART initiation at CD4≤500cells/μL, the valacyclovir scenario resulted in 167,000 fewer HIV infections over ten years, with an incremental cost-effectiveness ratio (ICER) of $5276 per HIV infection averted. A Test and Treat scenario with 70% ART coverage and no valacyclovir resulted in 350,000 fewer HIV infections at an ICER of $2822 and $812 per HIV infection averted and QALY gained, respectively.

CONCLUSION

Even when compared with valacyclovir suppression, a drug that reduces HIV viral load, universal treatment for HIV is the optimal strategy for averting new infections and increasing public health benefit. Universal HIV treatment would most effectively and efficiently reduce the HIV burden.

Human Herpesviruses as Copathogens of HIV Infection, Their Role in HIV Transmission, and Disease Progression

Of eight human herpesviruses (HHVs), often, only herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) find mention in medical literature as both of these viruses are commonly associated with genital lesions and oral ulcers, commonly known as cold sores. However, role of human herpesviruses as copathogens and in aggravation and in the transmission of other human diseases, especially the Acquired immunodeficiency syndrome (HIV/AIDS) has only very recently been recognized. Therefore, screening and treating subclinical HHV infections may offer slowing of HIV infection, disease progression, and its transmission. Beside HSV-1 and HSV-2, HHV-3 a causative agent of herpes zoster remained one of the first manifestations of HIV disease before the era of highly active antiretroviral therapy (HAART). HHV-5 also known as human Cytomegalovirus infection remains a significant risk factor for HIV-associated mortality and morbidity even in HAART era. It is proposed that Cytomegalovirus viremia could be a better predictor of HIV disease progression than CD4+ T-lymphocyte count. The role of HHV-4 or Epstein-Burr virus and HHV-6, HHV-7, and HHV-8 is still being investigated in HIV disease progression. This review provides insight into the current understanding about these 8 HHVs, their co-pathogenesis, and role in HIV/AIDS disease progression. The review also covers recent literature in favor and against administering anti-HHV treatment along with HAART for slower AIDS progression and interrupted sexual transmission.

Integrating prevention interventions for people living with HIV into care and treatment programs: a systematic review of the evidence

INTRODUCTION

This review assesses the impact of prevention interventions for people living with HIV on HIV-related mortality, morbidity, retention in care, quality of life, and prevention of ongoing HIV transmission in resource-limited settings (RLSs).

METHODS

We conducted a systematic review of studies reporting the results of prevention interventions for people living with HIV in RLS published between January 2000 and August 2014. Standardized methods of searching and data abstraction were used.

RESULTS

Ninety-two studies met the eligibility criteria: 24 articles related to adherence counseling and support, 13 on risk reduction education and condom provision, 19 on partner HIV testing and counseling, 14 on provision of family planning services, and 22 on assessment and treatment of other sexually transmitted infections. Findings indicate good evidence that adherence counseling and sexually transmitted infection treatment can have a high impact on morbidity, whereas risk reduction education, partner HIV testing and counseling, and family planning counseling can prevent transmission of HIV. More limited evidence was found to support the impact of these interventions on retention in care and quality of life. Most studies did not report cost information, making it difficult to draw conclusions about the cost-effectiveness of these interventions.

CONCLUSIONS

This evidence suggests that these prevention interventions, if brought to sufficient scale and coverage, can help support and optimize the impact of core treatment and prevention interventions in RLS. Further operational research with more rigorous study designs, and ideally with biomarkers and costing information, is needed to determine the best model for providing these interventions in RLS.

Cost-effectiveness of tenofovir gel in urban South Africa: model projections of HIV impact and threshold product prices

BACKGROUND

There is urgent need for effective HIV prevention methods that women can initiate. The CAPRISA 004 trial showed that a tenofovir-based vaginal microbicide had significant impact on HIV incidence among women. This study uses the trial findings to estimate the population-level impact of the gel on HIV and HSV-2 transmission, and price thresholds at which widespread product introduction would be as cost-effective as male circumcision in urban South Africa.

METHODS

The estimated 'per sex-act' HIV and HSV-2 efficacies were imputed from CAPRISA 004. A dynamic HIV/STI transmission model, parameterised and fitted to Gauteng (HIV prevalence of 16.9% in 2008), South Africa, was used to estimate the impact of gel use over 15 years. Uptake was assumed to increase linearly to 30% over 10 years, with gel use in 72% of sex-acts. Full economic programme and averted HIV treatment costs were modelled. Cost per DALY averted is estimated and a microbicide price that equalises its cost-effectiveness to that of male circumcision is estimated.

RESULTS

Using plausible assumptions about product introduction, we predict that tenofovir gel use could lead to a 12.5% and 4.9% reduction in HIV and HSV-2 incidence respectively, by year 15. Microbicide introduction is predicted to be highly cost-effective (under $300 per DALY averted), though the dose price would need to be just $0.12 to be equally cost-effective as male circumcision. A single dose or highly effective (83% HIV efficacy per sex-act) regimen would allow for more realistic threshold prices ($0.25 and $0.33 per dose, respectively).

CONCLUSIONS

These findings show that an effective coitally-dependent microbicide could reduce HIV incidence by 12.5% in this setting, if current condom use is maintained. For microbicides to be in the range of the most cost-effective HIV prevention interventions, product costs will need to decrease substantially.

Effects of valacyclovir on markers of disease progression in postpartum women co-infected with HIV-1 and herpes simplex virus-2

Objective

Herpes simplex virus type 2 (HSV-2) suppression has been shown to reduce HIV-1 disease progression in non-pregnant women and men, but effects on pregnant and postpartum women have not been described.

Methods

We analyzed data from a cohort of Kenyan women participating in a randomized clinical trial of HSV-2 suppression. Pregnant HIV-1-seropositive, HSV-2-seropositive women who were not eligible for antiretroviral therapy (WHO stage 1–2, CD4>250 cells/µl) were randomized to either 500 mg valacyclovir or placebo twice daily from 34 weeks gestation through 12 months postpartum. Women received zidovudine and single-dose nevirapine for prevention of mother-to-child HIV-1 transmission. HIV-1 progression markers, including CD4 count and plasma HIV-1 RNA levels, were measured serially. Multivariate linear regression was used to compare progression markers between study arms.

Results

Of 148 women randomized, 136 (92%) completed 12 months of postpartum follow-up. While adjusted mean CD4 count at 12 months (565 cells/µl placebo arm, 638 cells/µl valacyclovir arm) increased from antenatal levels in both arms, the mean CD4 count increase was 73 cells/µl higher in the valacyclovir arm than placebo arm (p = 0.03). Mean increase in CD4 count was 154 cells/µl in the valacyclovir arm, almost double the increase of 78 cells/µl in the placebo arm. At 12 months, adjusted HIV-1 RNA levels in the placebo arm increased by 0.66 log₁₀ copies/ml from baseline, and increased by only 0.21 log₁₀ copies/ml in the valacyclovir arm (0.40 log₁₀ copies/ml difference, p = 0.001).

Conclusion

Women randomized to valacyclovir suppressive therapy during pregnancy and postpartum had greater increases in CD4 counts and smaller increases in plasma HIV-1 RNA levels than women in the placebo arm. Valacyclovir suppression during pregnancy and breastfeeding may improve outcomes and delay antiretroviral therapy for HIV-1/HSV-2 co-infected women.